Oscillator structures oscillating in synchronization to an external clock signal are widely used. These are, for example, used to generate a signal having a predetermined duty cycle, i.e. a predetermined constant ratio between it's active (“1”) and it's inactive (“0”) phase. It is furthermore desirable that these oscillator structures are synchronized to the external clock signal, i.e. that the active phase at the oscillator structure output occurs at the same time or with fixed predetermined delay to the begin of the active phase of the clock signal, on which the oscillator structure is to be synchronized.
In the design phase of active circuits, it is often desirable to have access to adjustable oscillator structures, as then it might be possible to use the same oscillator structure (IC) for different design goals, instead of having to create an oscillator, which is specifically tailored to a unique circuit.